TM6SF2 E167K Research Articles

PNPLA3 is one of the bridges between TM6SF2 E167K variant and MASLD.

PNPLA3 is one of the bridges between TM6SF2 E167K variant and MASLD.

Human induced pluripotent stem cell based hepatic-modeling of lipid metabolism associated TM6SF2 E167K variant.

TM6SF2 rs58542926 (E167K) is related to increased prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD). Conflicting mouse study results highlight the need for a human model to understand this mutation's impact. This study aims to create and characterize a reliable human in vitro model to mimic the effects of the TM6SF2-E167K mutation for future studies. We used gene editing on human human-induced pluripotent stem cells (iPSC) from a healthy individual to create cells with the TM6SF2-E167K mutation. After hepatocyte directed differentiation, we observed decreased TM6SF2 protein expression, increased intracellular lipid droplets and total cholesterol in addition to reduced VLDL secretion. Transcriptomics revealed upregulation of genes involved in lipid, fatty acid, and cholesterol transport, flux, and oxidation. Global lipidomics showed increased lipid classes associated with ER stress, mitochondrial dysfunction, apoptosis, and lipid metabolism. Additionally, the TM6SF2-E167K mutation conferred a pro-inflammatory phenotype with signs of mitochondria and ER stress. Importantly, by facilitating protein folding within the ER of hepatocytes carrying TM6SF2-E167K mutation, VLDL secretion and ER stress markers improved. Our findings indicate that induced hepatocytes generated from iPSCs carrying the TM6SF2-E167K recapitulate the effects observed in human hepatocytes from individuals with the TM6SF2 mutation. This study characterizes an in vitro model that can be used as a platform to identify potential clinical targets and highlights the therapeutic potential of targeting protein misfolding to alleviate ER stress and mitigate the detrimental effects of the TM6SF2-E167K mutation on hepatic lipid metabolism.

Mechanism and therapeutic strategy of hepatic TM6SF2-deficient non-alcoholic fatty liver diseases via in vivo and in vitro experiments

BACKGROUNDThe lack of effective pharmacotherapies for nonalcoholic fatty liver disease (NAFLD) is mainly attributed to insufficient research on its pathogenesis. The pathogenesis of TM6SF2-efficient NAFLD remains unclear, resulting in a lack of therapeutic strategies for TM6SF2-deficient patients.AIMTo investigate the role of TM6SF2 in fatty acid metabolism in the context of fatty liver and propose possible therapeutic strategies for NAFLD caused by TM6SF2 deficiency.METHODSLiver samples collected from both NAFLD mouse models and human participants (80 cases) were used to evaluate the expression of TM6SF2 by using western blotting, immunohistochemistry, and quantitative polymerase chain reaction. RNA-seq data retrieved from the Gene Expression Omnibus database were used to confirm the over-expression of TM6SF2. Knockdown and overexpression of TM6SF2 were performed to clarify the mechanistic basis of hepatic lipid accumulation in NAFLD. MK-4074 administration was used as a therapeutic intervention to evaluate its effect on NAFLD caused by TM6SF2 deficiency.RESULTSHepatic TM6SF2 levels were elevated in patients with NAFLD and NAFLD mouse models. TM6SF2 overexpression can reduce hepatic lipid accumulation, suggesting a protective role for TM6SF2 in a high-fat diet (HFD). Downregulation of TM6SF2, simulating the TM6SF2 E167K mutation condition, increases intracellular lipid deposition due to dysregulated fatty acid metabolism and is characterized by enhanced fatty acid uptake and synthesis, accompanied by impaired fatty acid oxidation. Owing to the potential effect of TM6SF2 deficiency on lipid metabolism, the application of an acetyl-CoA carboxylase inhibitor (MK-4074) could reverse the NAFLD phenotypes caused by TM6SF2 deficiency.CONCLUSIONTM6SF2 plays a protective role in the HFD condition; its deficiency enhanced hepatic lipid accumulation through dysregulated fatty acid metabolism, and MK-4074 treatment could alleviate the NAFLD phenotypes caused by TM6SF2 deficiency.

Genetic Polymorphisms in Bulgarian Children with Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a multifactorial, highly prevalent liver disease in children. There is growing evidence that some genetic variants are associated with its development and rapid progression. The aim of this study was to assess the prevalence of specific single-nucleotide polymorphisms – PNPLA3 I148M, GCKR P446L, TM6SF2 E167K in Bulgarian children with NAFLD.
 We conducted a single-centre, prospective study of 32 children (22 patients with NAFLD and 10 healthy controls). Genetic testing and abdominal ultrasound were performed in all study participants. In the patients with NAFLD were additionally analyzed anthropometric parameters and standard biochemical tests, 10 of them underwent a liver biopsy for assessing disease activity and fibrosis.
 The most common polymorphism was GCKR P446L, detected in 75% of the studied population, followed by PNPLA3 I148M (50.0% of the studied population) and TM6SF2 E167K (9.4% of the studied population). The GCKRP446L gene variant was more common in patients with NAFLD than in healthy controls (86.4% vs. 50.0%, p = 0:03). Furthermore, significantly more patients with NAFLD were homozygous carriers of GCKR P446L compared to healthy controls (54.5% vs. 10.0%, p = 0:025). Both patients with histologically proven significant liver fibrosis were carriers of GCKR P446L.
 In the present study we found a high prevalence of GCKR P446L polymorphism among children with NAFLD, suggesting that this gene variant is associated with development of NAFLD in the Bulgarian pediatric population.

TM6SF2 E167K variant increases the severity of NAFLD in high fat diet-fed mice

TM6SF2 E167K variant increases the severity of NAFLD in high fat diet-fed mice

Construction of transmembrane 6 superfamily member 2 E167K gene knock-in mouse model by using CRISPR/Cas9 technology

Objective: To construct a transmembrane 6 superfamily member 2 (Tm6sf2) E167K gene knock-in mouse model. Methods: The plasmid was constructed to simultaneously express the single-stranded guide RNA Cas9 at a specific site of the mouse Tm6sf2 gene in the donor plasmid carrying the Tm6sf2 E167K fragment. The above two plasmids were injected into the mouse fertilized eggs together. The positive F0 generation mice were validated by PCR detection and sequencing. The number of F2 generation surviving mice in three genotypes of wild (Wt), heterozygous and knock-in (KI) were calculated. Wt and KI male mice (8 mice/ group) of F2 generation littermates were selected and given a normal diet for 8 weeks. The body weight of the mice was recorded every week, and the glucose metabolism and lipid metabolism indexes of the two mice were detected. The comparison between groups was performed with an independent sample t-test. Results: Genotype detection and sequencing results showed that the Tm6sf2 E167K gene knock-in mouse model was successfully established. KI mice had absence of homozygous lethal embryo phenotype. The body weight of KI mice was higher than that of Wt mice during lactation, and the difference between the two groups was statistically significant (P < 0.05).The fasting blood glucose of KI mice (9.50 ± 0.33)mmol/L was higher than that of Wt mice (7.80 ± 0.30)mmol/L, and the difference between the two groups was statistically significant (P < 0.05). During the oral glucose tolerance test, the 2-hour blood glucose level of KI mice (9.20 ± 0.51)mmol/L was higher than that of Wt mice (7.60 ± 0.18)mmol/L, and the difference between the two groups was statistically significant (P < 0.05). The liver triglyceride content of KI mice (8.40 ± 0.55)mg/g was higher than that of Wt mice (7.30 ± 0.63)mg/g, but the difference was not statistically significant (P > 0.05). There was no significant difference in plasma triglyceride levels between the two mice (P > 0.05). The Oil red O staining results showed that KI mice had more lipid accumulation in the centrilobular region of ​​liver than Wt mice. Conclusion: Tm6sf2 E167K gene knock-in mice were successfully constructed. Tm6sf2 E167K gene knock-in can cause abnormal glucose metabolism in mice and promote the occurrence of hepatic steatosis.

Independent and joint correlation of PNPLA3 I148M and TM6SF2 E167K variants with the risk of coronary heart disease in patients with non-alcoholic fatty liver disease

BackgroundCHD is reported to be the primary cause of death in patients with NAFLD. Genetic susceptibility genes contribute to the developmental risk of NAFLD or CHD. Whether the genetic factors could affect the risk of CHD in NAFLD patients is not clear. The aim of this study was to investigate the association of PNPLA3 I148M and TM6SF2 E167K variants with the risk of CHD in NAFLD patients in Chinese Han population.Patients and methodsPNPLA3 I148M and TM6SF2 E167K variants were genotyped in a cohort of 189 patients with NAFLD and CHD, as well as 242 patients with NAFLD and 242 healthy controls by gene sequencing. Additionally, serum lipids profiles were determined by standard clinical laboratory methods.ResultsThe minor allele frequency of PNPLA3 I148M and TM6SF2 E167K were 0.39 and 0.06 in this cohort, respectively. The distributions of PNPLA3 I148M genotypes and alleles were significant different in NAFLD group vs controls and in NAFLD+CHD group vs NAFLD group (all P < 0.05). NAFLD patients who carry the CG + GG genotype suffered the relative lower risk of CHD than CC genotype carriers (OR = 0.6, 95%CI: 0.40–0.90, P = 0.01). In addition, PNPLA3 I148M and TM6SF2 E167K possess the joint correlation with the decreased risk of CHD in NAFLD patients with the increased number of risk alleles. Besides, PNPLA3 I148M and TM6SF2 E167K variants associated with the decreased serum lipid levels in overall series.ConclusionsThere was a joint protective correlation of PNPLA3 I148M and TM6SF2 E167K variants with the developmental risk of CHD in NAFLD patients. PNPLA3 I148M and TM6SF2 E167K variants might correlated with the decreased risk of CHD in NAFLD patients by associated with the reduced serum lipid levels.

The TM6SF2 E167K genetic variant induces lipid biosynthesis and reduces apolipoprotein B secretion in human hepatic 3D spheroids

There is a high unmet need for developing treatments for nonalcoholic fatty liver disease (NAFLD), for which there are no approved drugs today. Here, we used a human in vitro disease model to understand mechanisms linked to genetic risk variants associated with NAFLD. The model is based on 3D spheroids from primary human hepatocytes from five different donors. Across these donors, we observed highly reproducible differences in the extent of steatosis induction, demonstrating that inter-donor variability is reflected in the in vitro model. Importantly, our data indicates that the genetic variant TM6SF2 E167K, previously associated with increased risk for NAFLD, induces increased hepatocyte fat content by reducing APOB particle secretion. Finally, differences in gene expression pathways involved in cholesterol, fatty acid and glucose metabolism between wild type and TM6SF2 E167K mutation carriers (N = 125) were confirmed in the in vitro model. Our data suggest that the 3D in vitro spheroids can be used to investigate the mechanisms underlying the association of human genetic variants associated with NAFLD. This model may also be suitable to discover new treatments against NAFLD.

Alcoholic liver disease: the roles of genetic-epigenetic factors and the effect of abstinence

The pathogenesis of alcoholic liver disease depends not only on the toxic effects of alcohol, but also on the complex interaction of host's and environmental factors. Thus, the genetic pre-disposition, co-morbidities and behavioral factors all play a role in the individual variations in the disease outcomes. On the other hand, the essential part of the therapeutic strategy is the complete withdrawal of the harmful etiological agent. The present paper is devoted to overview the genetics, the environmental factors and the effects of abstinence in alcoholic liver disease. Genetic variants in two enzymes involved in the metabolism of ethanol, alcohol-dehydrogenase ADH1B *2 and aldehyde-dehydrogenase ALDH2 *2 through increasing the blood level of acetaldehyde, may play a "protective" role against alcoholism. The P450 CYP2E1 *5 c2, an inducible microsomal oxidase, upregulated by ethanol and by formation of acetaldehyde and reactive oxygen species, increases liver toxicity. Three novel gene polymorphisms - such as the patatin-like phospholipase domain-containing 3 (PNPLA3 I148M C>G), the transmembrane 6 superfamily member 2 (TM6SF2 E167K), and the membrane-bound O-acyltransferase domain-containing 7 (MB0AT7 rs641738 C>T) - have been proven as risk factors of steatosis, fibrosis and even hepatocellular carcinoma in both alcoholic and non-alcoholic fatty liver disease patients. Alcohol-induced epigenetic effects, reversible but inheritable gene expression alterations - as histon modulations, DNA methylation and micro-RNA-s - are of importance in the pathogenesis as well, and in the future, they may serve as diagnostic markers and therapeutic targets. Women are at greater risk of developing alcoholic cirrhosis, furthermore, malnutrition, obesity, diabetes, smoking, and hepatitis virus infections are also risk factors. Alcoholic liver disease should be regarded as a preventable disease. Several clinical studies revealed that abstinence may result in the regression of steatohepatitis and fibrosis, compensation of cirrhosis, improving disease outcome and increasing survival even in patients with advanced stages. Early diagnosis and multidisciplinary interventions are highly required to achieve long-term abstinence and to prevent alcoholic cirrhosis. Orv Hetil. 2019; 160(14): 524-532.

Combining I148M and E167K variants to improve risk prediction for nonalcoholic fatty liver disease in Qingdao Han population, China

BackgroundPNPLA3 I148M variant and TM6SF2 E167K variant are recognized as the major genetic modifiers of nonalcoholic fatty liver disease (NAFLD). The present study sought to evaluate the potential additive effect of the two variants on the risk of NAFLD in Qingdao Han Population, China.MethodsWe genotyped PNPLA3 I148M variant and TM6SF2 E167K variant in a cohort of 512 unrelated NAFLD patients and 451 healthy controls by sequencing and polymerase chain reaction analysis. In addition, serum lipid profiles and liver enzymes were determined by standard clinical laboratory methods.ResultsThe minor allele frequencies were 45.48% for PNPLA3 148 locus G allele and 6.69% for TM6SF2 167 locus T allele. The PNPLA3 I148M variant was significantly associated with the risk of NAFLD in an additive model (CG, OR = 2.092, 95% CI: 1.551–2.820, P = 0.000; GG, OR = 4.566, 95% CI: 3.141–6.638, P = 0.000, respectively). And, our data suggested a strong link between the TM6SF2 E167K variant and the risk of NAFLD in a dominant model (CT + TT, OR = 2.327, 95% CI: 1.542–3.513, P = 0.000). In addition, the increasing of the number of risk alleles were associated with the risk of NAFLD (1 risk allele, OR = 1.687, P = 0.001; 2 risk alleles, OR = 4.326, P = 0.000; 3 risk alleles, OR = 6.018, P = 0.027, respectively).ConclusionsCombining the I148M and E167K variants in a manner of an additive effect could improve risk prediction for NAFLD in a Qingdao Han Population cohort.Trial registrationChinese Clinical Trial Register.gov: ChiCTR1800015426.

The additive effects of the TM6SF2 E167K and PNPLA3 I148M polymorphisms on lipid metabolism.

There is a genetic susceptibility for nonalcoholic fatty liver disease (NAFLD). To examine the role of genetic factors in the disease, a Bayesian analysis was performed to model gene relationships in NAFLD pathogenesis. The Bayesian analysis indicated a potential gene interaction between the TM6SF2 and PNPLA3 genes. Next, to explore the underlying mechanism at the cellular level, we evaluated the additive effects between the TM6SF2 E167K and PNPLA3 I148M polymorphisms on lipid metabolism. Hepa 1-6 cells were transfected with a control vector or with overexpression vectors for TM6SF2/PNPLA3-wild type, TM6SF2-mutant type, PNPLA3-mutant type, or TM6SF2/PNPLA3-mutant type. Commercial kits were used to measure triglyceride and total cholesterol levels in each of the five groups. The mRNA and protein expression levels of sterol regulatory element-binding transcription factor 1c and fatty acid synthase were analyzed using real-time PCR and western blotting. The triglyceride and total cholesterol contents were significantly different among the groups. The triglyceride and total cholesterol contents and the sterol regulatory element-binding transcription factor 1c and fatty acid synthase mRNA and protein expression levels were significantly higher in the TM6SF2/PNPLA3-mutant type group than in the TM6SF2-mutant type group or the PNPLA3-mutant type group. The TM6SF2 E167K and PNPLA3 I148M polymorphisms may have additive effects on lipid metabolism by increasing the expression of sterol regulatory element-binding transcription factor 1c and fatty acid synthase.

E167K polymorphism of TM6SF2 gene affects cell cycle of hepatocellular carcinoma cell HEPA 1-6

BackgroundSome studties reported that the polymorphism of TM6SF2 gene E167K affects the occurrence and the progression of hepatocytes carcinoma (hepatocellular, HCC). In oeder to investigate the effects of the polymorphism of TM6SF2 gene E167K in the pathogenesis of HCC, we explored its influence on the cell cycle in hepatocellular carcinoma cell HEPA1-6.MethodsHEPA 1–6 cells which could respectively overexpress TM6SF2 wild type and E167K variant were cultured and HEPA 1–6 cells with zero load plasmids were used as matched control. Flow cytometry was used to detect the cell cycles of these 3 type of HEPA 1–6 cells. Realtime fluores-cence quantitative PCR and western blot were used to analyzed the expression of regulatory factors (Cyclin D1、p53、P16、P27、P21 and Rb) of cell cycle. T-test was used in statistical analysis.ResultsCell cycle phase distribution was presented by the proportion of cells in each phases (%). Compared with the control group, the cell cycle phase distribution (G1 phase 57.36 ± 0.21%, G2/M phase 25.61 ± 0.36%,S phases 19.31 ± 0.25%) had no differences in wild type group (G1 phase 57.63 ± 0.28%, G2/M phase 25.77 ± 0.51%, S phases 19.54 ± 0.25%; P < 0.05). Between variant type group and wild type group,G1 phase was significantly decreased (variant type group G1 phase 36.26 ± 0.31%, P < 0.05),S phase and G2/M phase were increased(variant type group S phase 28.41 ± 0.31%, P < 0.05;G2/M phase 35.23 ± 0.14%, P < 0.05), respectively. Compared with control group,the relative expression of CyclinD1、P53 and Rb mRNA in variant type group was significantly upregulated (2.03 ± 0.01 VS 1.04 ± 0.06, 1.88 ± 0.05 VS 1.37 ± 0.03, 1.29 ± 0.06 VS 1.15 ± 0.03, P < 0.05) and P27 mRNA in variant type group was significantly downregulated (0.56 ± 0.02 VS 0.85 ± 0.05, P < 0.05).Compared with wild type group, the relative expression of CyclinD1、P53 and Rb mRNA in variant type group was significantly upregulated (wild type group 1.00 ± 0.00, 1.48 ± 0.09, 1.18 ± 0.01, P < 0.05) and P27 mRNA in variant type group was significantly downregulated (variant type group 0.82 ± 0.05,P < 0.05). There was no statistical significance between wild type group and control group (P > 0.05). P16 and P21 expression showed no statistical sigtfificance in any of these three groups (P > 0.05).ConclusionE167K polymorphism of TM6SF2 gene affects cell cycles of HEPA1–6 cells via up-regulating CyclinD1、P53 and Rb and down-regulating P27.

Impaired hepatic lipid synthesis from polyunsaturated fatty acids in TM6SF2 E167K variant carriers with NAFLD

Carriers of the transmembrane 6 superfamily member 2 E167K gene variant (TM6SF2EK/KK) have decreased expression of the TM6SF2 gene and increased risk of NAFLD and NASH. Unlike common 'obese/metabolic' NAFLD, these subjects lack hypertriglyceridemia and have lower risk of cardiovascular disease. In animals, phosphatidylcholine (PC) deficiency results in a similar phenotype. PCs surround the core of VLDL consisting of triglycerides (TGs) and cholesteryl-esters (CEs). We determined the effect of the TM6SF2 E167K on these lipids in the human liver and serum and on hepatic gene expression and studied the effect of TM6SF2 knockdown on hepatocyte handling of these lipids. Liver biopsies were taken from subjects characterized with respect to the TM6SF2 genotype, serum and liver lipidome, gene expression and histology. In vitro, after TM6SF2 knockdown in HuH-7 cells, we compared incorporation of different fatty acids into TGs, CEs, and PCs. The TM6SF2EK/KK and TM6SF2EE groups had similar age, gender, BMI and HOMA-IR. Liver TGs and CEs were higher and liver PCs lower in the TM6SF2EK/KK than the TM6SF2EE group (p<0.05). Polyunsaturated fatty acids (PUFA) were deficient in liver and serum TGs and liver PCs but hepatic free fatty acids were relatively enriched in PUFA (p<0.05). Incorporation of PUFA into TGs and PCs in TM6SF2 knockdown hepatocytes was decreased (p<0.05). Hepatic expression of TM6SF2 was decreased in variant carriers, and was co-expressed with genes regulated by PUFAs. Hepatic lipid synthesis from PUFAs is impaired and could contribute to deficiency in PCs and increased intrahepatic TG in TM6SF2 E167K variant carriers.

Meta-analysis of the influence of TM6SF2 E167K variant on Plasma Concentration of Aminotransferases across different Populations and Diverse Liver Phenotypes

A nonsynonymous E167K (rs58542926 C/T) variant in TM6SF2 gene was recently associated with nonalcoholic fatty liver disease (NAFLD). We explored the association between E167K and plasma concentrations of alanine (ALT) and aspartate (AST) aminotransferases through a meta-analysis. We also estimated the strength of the effect across diverse liver phenotypes, including NAFLD and chronic viral hepatitis; fourteen studies were included. We found that ALT (p = 3.2 × 10−6, n = 94,414) and AST (p = 0007, n = 93,809) levels were significantly associated with rs58542926 in NAFLD. By contrast, rs58542926 was not associated with either ALT (p = 0.24, n = 4187) or AST (p = 0.17, n = 2678) levels in four studies on chronic hepatitis. In conclusion, the results of the pooled estimates in patients with NAFLD showed that carriers of the T allele (EK + KK), when compared with homozygous subjects for the C allele (EE genotype) have increased levels of aminotransferases; however, this increase represents –2.5 (9.8%) and 1.2 (5%) IU/L of ALT and AST respectively, which is fairly small compared with the large effect of PNPLA3- rs738409-G allele that is associated with a –28% increase in serum ALT.

The dual and opposite role of the TM6SF2-rs58542926 variant in protecting against cardiovascular disease and conferring risk for nonalcoholic fatty liver: A meta-analysis.

The aim of this work was to estimate the strength of the effect of the TM6SF2 E167K (rs58542926 C/T) variant on blood lipid traits and nonalcoholic fatty liver disease (NAFLD) across different populations. We performed a systematic review by a meta-analysis; literature searches identified 10 studies. The rs58542926 exerts a significant role in modulating lipid traits, including total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and NAFLD. However, this influence on lipids and NAFLD is opposite between genotypes in the dominant model of inheritance. Pooled estimates of random effects in 101,326 individuals showed that carriers of the minor T allele (EK+KK individuals), compared with subjects homozygous for the ancestral C allele (EE genotype), are protected from cardiovascular disease (CVD), showing lower levels of TC, LDL-C, and TG; the differences in mean ± standard error (mg/dL) are -8.38 ± 1.56, -3.7 ± 0.9, and -9.4 ± 2.1, respectively. The rs58542926 variant was not associated with high-density lipoprotein cholesterol in a large sample (n = 91,937). In contrast, carriers of the T allele showed a moderate effect on the risk of NAFLD (odds ratio: 2.13; 95% confidence interval: 1.36-3.30; P = 0.0009; n = 3273) and approximately ∼2.2% higher lipid fat content when compared with homozygous EE (n = 3,413). The rs58542926 appears to be an important modifier of blood lipid traits in different populations. As a challenge for personalized medicine, the C-allele, which has an overall frequency as high as 93%, is associated with higher blood lipids, whereas the T allele confers risk for NAFLD; in turn, CVD and NAFLD are strongly related outcomes. Although the variant confers protection against CVD at the expense of an increased risk of NAFLD, it does not explain the link between these two complex diseases.

Treating liver fat and serum triglyceride levels in NAFLD, effects of PNPLA3 and TM6SF2 genotypes: Results from the WELCOME trial

Genetic variation in both patatin-like phospholipase domain-containing protein-3 (PNPLA3) (I148M) and the transmembrane 6 superfamily member 2 protein (TM6SF2) (E167K) influences severity of liver disease, and serum triglyceride concentrations in non-alcoholic fatty liver disease (NAFLD), but whether either genotype influences the responses to treatments is uncertain. One hundred three patients with NAFLD were randomised to omega-3 fatty acids (DHA+EPA) or placebo for 15-18months in a double blind placebo controlled trial. Erythrocyte enrichment with DHA and EPA was measured by gas chromatography. PNPLA3 and TM6SF2 genotypes were measured by PCR technologies. Multivariable linear regression and analysis of covariance were undertaken to test the effect of genotypes on omega-3 fatty acid enrichment, end of study liver fat percentage and serum triglyceride concentrations. All models were adjusted for baseline measurements of each respective outcome. Fifty-five men and 40 women (Genotypes PNPLA3 I148M, 148I/I=41, 148I/M=43, 148M/M=11; TM6SF2 E167K 167E/E=78, 167E/K+167K/K=17 participants) (mean ± SD age, 51 ± 11 years) completed the trial. Adjusting for baseline measurement, measured covariates and confounders, PNPLA3 148M/M variant was independently associated with percentage of DHA enrichment (B coefficient -1.02 (95% CI -1.97, -0.07), p=0.036) but not percentage of EPA enrichment (B coefficient -0.31 (95% CI -1.38, 0.75), p=0.56). This genotype was also independently associated with end of study liver fat percentage (B coefficient 9.5 (95% CI 2.53, 16.39), p=0.008), but not end of study triglyceride concentration (B coefficient -0.11 (95% CI -0.64, 0.42), p=0.68). PNPLA3 148M/M variant influences the changes in liver fat and DHA tissue enrichment during the trial but not the change in serum triglyceride concentration.

Statin use and non-alcoholic steatohepatitis in at risk individuals

Excess hepatic free cholesterol contributes to the pathogenesis of non-alcoholic steatohepatitis, and statins reduce cholesterol synthesis. Aim of this study was to assess whether statin use is associated with histological liver damage related to steatohepatitis. The relationship between statin use, genetic risk factors, and liver damage was assessed in a multi-center cohort of 1201 European individuals, who underwent liver biopsy for suspected non-alcoholic steatohepatitis. Statin use was recorded in 107 subjects, and was associated with protection from steatosis, NASH, and fibrosis stage F2-F4, in a dose-dependent manner (adjusted p<0.05 for all). In 100 treated patients matched 1:1 for modality of recruitment, gender, presence of IFG or type 2 diabetes, PNPLA3 I148M risk alleles, TM6SF2 E167K variant, age, and BMI, statin use remained associated with protection from steatosis (OR 0.09, 95% C.I. 0.01-0.32; p=0.004), steatohepatitis (OR 0.25, 95% C.I. 0.13-0.47; p<0.001), and fibrosis stage F2-F4 (OR 0.42, 95% C.I. 0.20-0.8; p=0.017). Results were confirmed in a second analysis, where individuals were matched within recruitment center (p<0.05 for all). The protective effect of statins on steatohepatitis was stronger in subjects not carrying the I148M PNPLA3 risk variant (p=0.02 for interaction), as statins were negatively associated with steatohepatitis in patients negative (p<0.001), but not in those positive for the I148M variant (p=n.s.). Statin use was associated with protection towards the full spectrum of liver damage in individuals at risk of non-alcoholic steatohepatitis. However, the I148M PNPLA3 risk variant limited this beneficial effect.

O065 : Mechanistic study of TM6SF2 in NAFLD pathogenesis: Stably transfected Huh7 cells over-expressing the TM6SF2 E167K variant exhibit greater levels of oxidative stress

O065 : Mechanistic study of TM6SF2 in NAFLD pathogenesis: Stably transfected Huh7 cells over-expressing the TM6SF2 E167K variant exhibit greater levels of oxidative stress

Paradoxical dissociation between hepatic fat content and de novo lipogenesis due to PNPLA3 sequence variant.

Nonalcoholic fatty liver disease (NAFLD) is an emerging epidemic disease characterized by increased hepatic fat, due to an imbalance between synthesis and removal of hepatic lipids. In particular, increased hepatic de novo lipogenesis (DNL) is a key feature associated with NAFLD. The genetic variations I148M in PNPLA3 and E167K in TM6SF2 confer susceptibility to NAFLD. Here we aimed to investigate the contribution of DNL to liver fat accumulation in the PNPLA3 I148M or TM6SF2 E167K genetic determinants of NAFLD. The PNPLA3 I148M and TM6SF2 E167K were genotyped in two well-characterized cohorts of Europeans. In the first cohort (Helsinki cohort; n = 88), we directly quantified hepatic DNL using deuterated water. In the second cohort (Milan cohort; n = 63), we quantified the hepatic expression of SREBP1c that we have found previously associated with increased fat content. Liver fat was measured by magnetic resonance proton spectroscopy in the Helsinki cohort, and by histological assessment of liver biopsies in the Milan cohort. PNPLA3 148M was associated with lower DNL and expression of the lipogenic transcription factor SREBP1c despite substantial increased hepatic fat content. Our data show a paradoxical dissociation between hepatic DNL and hepatic fat content due to the PNPLA3 148M allele indicating that increased DNL is not a key feature in all individuals with hepatic steatosis, and reinforces the contribution of decreased mobilization of hepatic triglycerides for hepatic lipid accumulation in subject with the PNPLA3 148M allele.

TM6SF2 E167K variant is associated with severe steatosis in chronic hepatitis C, regardless of PNPLA3 polymorphism.

A common non-synonymous polymorphism, E167K, in transmembrane six superfamily member 2 (TM6SF2) gene has been recently associated with an increased hepatic triglyceride content, dyslipidemia and liver fibrosis in NAFLD patients. We investigated possible associations between the TM6SF2 variants and liver lesions in chronic hepatitis C. 148 consecutive patients with biopsy proven anti-HCV/HCV-RNA-positive chronic hepatitis, naive for antiviral therapy, were genotyped for TM6SF2 E167K and PNPLA3 I148M variants. The score of liver steatosis was higher in the 18 patients with TM6SF2 E167K variant (mean 1.9 ± 1.3) than in the 130 homozygotes for TM6SF2 167E allele (1.1 ± 1.1, P = 0.02), and the prevalence of a steatosis score ≥ 3 was 33.3% vs. 12.3% respectively (P = 0.02). No difference in necroinflammatory or fibrosis scores was found between the two groups. A general linear model identified as independent predictors of steatosis TM6SF2 E167K and PNPLA3 M148M variants and waist circumference (P = 0.0376, P = 0.0069 and P = 0.0273 respectively). This is the first demonstration that TM6SF2 E167K variant is an independent predictor of liver steatosis in chronic hepatitis C.